Synchrotron radiation Marcin Sikora Academic Centre for Materials - PowerPoint PPT Presentation

Synchrotron radiation Marcin Sikora Academic Centre for Materials and Nanotechnology, AGH-UST, Krakow, Poland marcin.sikora@agh.edu.pl ESM-2018, Krakow, 26/9/2018 1

Origin of light 1. Charge: a source of electric field, 𝑬 = 𝜁 0 𝑭 . 2. Charge motion results in variable field, 𝜖𝑬 𝑒𝑢 ≠ 0 , a source of perpendicular magnetic field, 𝑪 = 𝜈 0 𝑰. thebigblogtheory.wordpress.com 3. Variable magnetic field, 𝜖𝑰 𝑒𝑢 ≠ 0 , a source of perpendicular 𝑭 field … Emission of light (E-M wave) ߲ 2 𝑭 𝑒𝑢 2 ≠ 0 , requires that i.e. acceleration of charge ~ ESM-2018, Krakow, 26/9/2018 2

Origin of synchrotron light Electric dipol 𝒃 𝒃 Electron in ring Electron in ring centripetal force relativistic 𝒃 𝒃 ESM-2018, Krakow, 26/9/2018 3

Synchrotron light spectrum Critical energy Orbital radius 𝒃 Radiated power ESM-2018, Krakow, 26/9/2018 4

𝑔 = 𝑑 𝜇 Electromagnetic spectrum nasa.gov; www.lightsources.org ESM-2018, Krakow, 26/9/2018 5

LHC: 27km ESRF: 840m Topology of synchrotrons CLS:171m 234m lightsources.org, cern.ch, lynceantech.com ERL: 768m+ ~10m ESM-2018, Krakow, 26/9/2018 6

Outline Development of SR sources Properties of SR, instrumentation Applications of SR • diffraction • imaging • spectroscopy Applications to magnetism • magnetic structure • element selective magnetometry • magnetic imaging • time resolved study • extreme conditions ESM-2018, Krakow, 26/9/2018 7

Theoretical and experimental foundations Appleyard R. Electrical Communication 6 (1927) 63 1865: J.C.Maxwell’s paper A Dynamical Theory of the Electromagnetic Field 1887: experimental observation of E-M waves by H.Hertz 1897: discovery of electron by J.J.Thompson 1898- 1900: Liénard and Wiechert formulate the theory of retarded potential 1907: G.A.Schott’s formulates the full theory of radiation from electrons travelling at close to the speed of light ESM-2018, Krakow, 26/9/2018 8

Cyclic particle accelerators 1932: First cyclotron build by S. Gaál and E.O.Lawrence (4.8 MeV,  = 69 cm) 1935: First betatron build by M.Steenbeck (original concept from Rolf Widerøe ) wikipedia.org 1944- 1945: First synchrotrons by Vladimir Veksler and Edvin McMillan’s ESM-2018, Krakow, 26/9/2018 9

Discovery 1944: Ivanenko and Pomeranchouk calculate energy loss of electrons in betatron 1945: observation of modified trajectory of electrons in 100MeV betatron (Blewett), no traces of radiation detected 1947, April 24: Pollock, Langmuir, Elder and Gurewitsch observe light produced inside vacuum tube of newly built 70MeV synchrotron (GE, Schenectady, Nowy Jork), called synchrotron radiation 1949: Schwinger’s theory of SR 1969: Ginzburg & Syrovatskiy publish Development of the Theory of Synchrotron Radiation and Its Reabsorption based on Shklovsky’s theory of cosmic radiation ESM-2018, Krakow, 26/9/2018 10

Synchrotron lattice Replenishment of electron energy and longitudinal focussing using RF cavities Willmott P. An Introduction to Synchrotron Radiation, Willey 2011 „Race track” synchrotron by D. Crane (Univ. of Michigan, 1949) Guiding and lateral focussing of el. bunches using magnets : dipole, quadrupole, sextupole, N- pole … ESM-2018, Krakow, 26/9/2018 11

Insertion devices Maximum angular deviation of the electron orbit, 𝜚 𝑛𝑏𝑦 , define undulator parameter: Wavelength shifter Undulator K~1 𝐽 𝑞𝑓𝑏𝑙 ~𝑜 𝑓𝑚 𝑂 2 Wiggler K~10 𝐽 𝑛𝑏𝑦 ~𝑜 𝑓𝑚 𝑂 Willmott P. An Introduction to Synchrotron Radiation, Willey 2011 ESM-2018, Krakow, 26/9/2018 12

Generations of SR sources 4 th : optimized for coherence free electron lasers (FEL) & diffraction limited storage rings (DLSR) 3 rd : optimized for brilliance (insertion devices) 2 nd : dedicated storage rings 1 st : refurbished storage rings & parasitic operation Willmott P. An Introduction to Synchrotron Radiation, Willey 2011 ESM-2018, Krakow, 26/9/2018 13

Generations of SR sources 4 th : optimized for coherence free electron lasers (FEL) & diffraction limited Willmott P. An Introduction to Synchrotron Radiation, Willey 2011 storage rings (DLSR) 3 rd : optimized for brilliance (insertion devices) 2 nd : dedicated storage rings 1 st : refurbished storage rings & parasitic operation ESM-2018, Krakow, 26/9/2018 14

Unique properties od SR • Stable, high flux source of photons • Broad spectrum • Collimated and coherent • Discrete time structure • Polarized (linearly, circularly) e - Attwood D. Soft X-Rays and Extreme Ultraviolet Radiation, Cambridge University Press 1999 ESM-2018, Krakow, 26/9/2018 15

Synchrotron radiation labs There are more than 50 light sources in the world (operational, or under construction). Most of them offer free of charge access upon succesful beamtime applications (peer-reviewed). www.lightsources.org ESM-2018, Krakow, 26/9/2018 16

Elements of X-ray optics and instrumentation www.synchrotron.pl Slits Mirrors Monochromators deflecting Detectors/endstations & focusing ESM-2018, Krakow, 26/9/2018 17

http://ftp.esrf.fr/pub/scisoft/xop2.3/ X-ray mirrors Deflection Focusing Filtering cut-off energy ESM-2018, Krakow, 26/9/2018 18

Monochromators Pinhole Grating VUV & soft X-rays Attwood D. Soft X-Rays and Extreme Ultraviolet Radiation, Cambridge University Press 1999 ESM-2018, Krakow, 26/9/2018 19

Monochromators Crystals, multilayers hard X-rays bent crystals/gratings Bragg law Rowland circle geometry 𝑏 𝑜𝜇 = 2 ℎ 2 + 𝑙 2 +𝑚 2 𝑡𝑗𝑜𝜄 Attwood D. Soft X-Rays and Extreme Ultraviolet Radiation, Cambridge University Press 1999 ESM-2018, Krakow, 26/9/2018 20

Focusing optics Coated glass capilary Compound refractive lenses hard X-rays hard X-rays Fresnel zone plates soft X-rays Willmott P. An Introduction to Synchrotron Radiation, Willey 2011 ESM-2018, Krakow, 26/9/2018 21

Detectors • Ionization chambers • Scintilators • Si/Ge pin diodes • Silicon drift detectors (SDD) • Avalanche photodiode (APD) • Position sensitive detectors (PSD) • Photocurent • Drain current • Phosphor screen + CCD • …. www.ketek.net; www.dectris.com; www.hamamatsu.com; www.canberra.com ESM-2018, Krakow, 26/9/2018 22

Outline Development of SR sources Properties of SR, instrumentation Applications of SR • diffraction • imaging • spectroscopy Applications to magnetism • magnetic structure • element selective magnetometry • magnetic imaging • time resolved study • extreme conditions ESM-2018, Krakow, 26/9/2018 23

Applications of synchrotron radiation X-ray diffraction Vimeo.com/diamondlightsource ESM-2018, Krakow, 26/9/2018 24

Applications of synchrotron radiation X-ray diffraction Crystal structure of proteins e.g. RuBisCO enzyme active sites, where CO 2 is bound www.wikipedia.org ESM-2018, Krakow, 26/9/2018 25

Applications of synchrotron radiation Time resolved and in-situ study Release of oxygen from Myoglobine protein Courtesy: esrf.eu ESM-2018, Krakow, 26/9/2018 26

Applications of synchrotron radiation Phase contrast image Coherent photon beam ~20 m m lateral size up to 150m projection Contrast due to small variations of refractive index Courtesy: esrf.eu ESM-2018, Krakow, 26/9/2018 27

Applications of synchrotron radiation Phase contrast tomography Non-destructive testing of fossils e.g. anatomical details of ancient snakes Courtesy: esrf.eu ESM-2018, Krakow, 26/9/2018 28

Interaction of X-rays with matter henke.lbl.gov ESM-2018, Krakow, 26/9/2018 29

X-ray absorption 4p TM K -edge E F 3d 1s RE L 3 , L 2 , L 1 edges Dipol selection rules: ∆𝑚 = ±1 ∆𝑘 = ±1 𝑝𝑠 0 D s = 0 Element selective & symmetry sensitive probe of unoccupied electronic structure ESM-2018, Krakow, 26/9/2018 30

Magnetic scattering and absorption Atomic form factor     =   f f f ' E if " E 0 C.C. Kao at al., Phys. Rev. B (1994) Elastic Reflectivity Absorption Magnetic vs. charge scattering f charge f ~  magnetic 2 4 10    f magnetic ~ A L B S Spin Orbital ESM-2018, Krakow, 26/9/2018 31

X-ray magnetic circualar dichroism 𝑪 𝒇𝒚𝒖 3d E F Mass absorption 2p 3/2 m  2p 1/2 m  G. van der Laan, J. Phys.: Conf. Series (2013) L 3 L 2 Photon energy D m ESM-2018, Krakow, 26/9/2018 32

Sum rules B.T.Thole et al., PRL 68 (1992) 1943 P.Carra et al., PRL 70 (1993) 694 where n denotes the number of holes in the final states Enable to separate spin and orbital moments ESM-2018, Krakow, 26/9/2018 33

Magnetic X-ray microscopy XMCD using ultrasmall X-ray beam or magnification optics & position sensitive detector for photons/photoelectrons A.P. Hitchcock, J. Electron Spectrosc. Relat. Phenom. (2015) ESM-2018, Krakow, 26/9/2018 34

Magnetic X-ray microscopy 3d E F XMCD contrast proportional to the magnetization projection on incoming photon direction 2p 3/2 2p 1/2 F. Noltig in Magnetism and Synchrotron Radiation New Trends, Springer 2010 ESM-2018, Krakow, 26/9/2018 35